Optical Sensor With TFT Current Amplifier for Backlight Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical sensors for transmissive display apparatuses, which use amorphous thin-film transistors (a-Si TFTs), face challenges in amplifying a leak current to control backlight luminance effectively, as they require separate manufacturing processes for the TFT and bipolar transistor, increasing the number of manufacturing steps and complicating integration with the display unit.
Innovation Solution
An optical sensor configuration utilizing a photoelectric converter, current-to-voltage converter, voltage amplifier, and current amplifier, all incorporating at least one thin-film transistor, allows for the amplification of photocurrent signals to control backlight illuminance, enabling the same manufacturing process for both the optical sensor and display unit, with a-Si TFTs used for both components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a bipolar transistor is used to amplify photocurrent signal, then the amplification effect is improved, but the manufacturing process complexity increases because TFT and bipolar transistor require different manufacturing processes
Solution Approach 1:
The patent combines the photodetector and amplifier into a single integrated structure where the photodetector is formed in the channel region of the TFT. This integration allows both components to be manufactured using the same TFT fabrication process, eliminating the need for separate bipolar transistor manufacturing while maintaining effective current amplification capability.
Solution Approach 2:
The TFT serves multiple functions: it acts as both the switching transistor for the display pixel and as the amplifier transistor for the photodetector signal. The channel region of the TFT functions as the photodetector active area, while the same TFT structure provides the amplification function, achieving multi-functionality with a single device type.
2Power
If separate manufacturing processes are used for TFT and bipolar transistor, then the amplification performance is improved, but the integration with display unit becomes more difficult
Solution Approach 1:
The photodetector and amplifier are merged into a single integrated device where the photodetector is formed within the channel region of the TFT. This merging enables both components to be fabricated simultaneously using the same manufacturing process steps, greatly simplifying integration with the display unit while maintaining effective signal amplification.
3Ease of manufacture
If amorphous thin-film transistor is used for optical sensor, then the manufacturing process integration is improved, but the leak current amplification capability is insufficient
Solution Approach 1:
The patent merges the photodetector and amplifier functions into a single TFT structure, where the photodetector is formed in the channel region. This integration enables effective current amplification capability while maintaining the manufacturing process integration benefits of using amorphous thin-film transistors for both the optical sensor and display unit.
Solution Approach 2:
The patent utilizes the channel region dimension of the TFT as the photodetector active area, creating a new functional dimension within the existing TFT structure. This dimensional utilization enables the TFT to simultaneously function as both a switching device and a photodetector-amplifier combination, achieving sufficient current amplification while maintaining manufacturing integration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively amplifies photocurrent signals, enabling precise control of backlight illuminance while maintaining a compact design and reducing manufacturing complexity by using a-Si TFTs for both the optical sensor and display unit, improving viewability and power efficiency.
Implementation Method 1
a photoelectric converter to receive external light, and to output a photocurrent signal according to the illuminance of the external light
Data Source
AI summary
An optical sensor includes a photoelectric converter to receive external light and to output a photocurrent signal according to the illuminance of the external light. A current-to-voltage converter converts the photocurrent signal output from the photoelectric converter to a voltage signal. A voltage amplifier amplifies the voltage signal. A current amplifier outputs a current signal corresponding to the voltage signal amplified by the voltage amplifier. Each of the photoelectric converter, current-to-voltage converter, voltage amplifier and current amplifier includes at least one thin-film transistor.